Diagnostic Procedure

2000 Saturn LS1 AutomaticSECTION Diagnostic Procedure

Diagnosis of computerized engine control system should be performed in the following order:

  1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. On-Board Diagnostic (OBD) system check must be performed before using specific DTC testing procedure. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK .
  2. If DTCs were displayed, determine whether DTCs are hard or intermittent. Hard DTCs will cause MIL to illuminate continuously while engine is running. See HARD OR INTERMITTENT TROUBLE CODE DETERMINATION . For diagnosing hard DTCs, proceed to appropriate DTC test. See DIAGNOSTIC TESTS . For diagnosing intermittent DTCs, see appropriate TROUBLE SHOOTING - NO CODES article.
  3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in appropriate TROUBLE SHOOTING - NO CODES article. Doing so will help identify proper system or component to check in appropriate SYSTEM & COMPONENT TESTING article.
  4. After necessary repairs are made, clear DTCs, verify vehicle will enter "closed loop" operation and ensure DTC does not reset.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.